Suspension systems for one-wheeled vehicles

ABSTRACT

A self-balancing electric vehicle may include a board having a frame, and a suspension system including at least one four-bar linkage coupling opposing end portions of a hub motor axle to the first end portion of the frame. The four-bar linkage(s) may have a first fixed link connected to the axle, a second fixed link comprising the frame, and two pivotable links joining the first fixed link to the second fixed link, such that the board is configured to be movable up and down relative to the axle. A shock absorber may be coupled to the four-bar linkage(s) and to the first end portion of the frame, such that the shock absorber is configured to damp up and down movement of the board relative to the axle.

FIELD

This disclosure relates to systems and methods for isolating aone-wheeled vehicle frame from certain effects of uneven terrain. Morespecifically, the disclosed embodiments relate to suspension systems forone-wheeled vehicles.

SUMMARY

The present disclosure provides systems, apparatuses, and methodsrelating to suspension systems for one-wheeled vehicles.

In some embodiments, a self-balancing electric vehicle may include: aboard including a frame, a first deck portion disposed at a first endportion of the frame, and a second deck portion disposed at a second endportion of the frame, the first and second deck portions each configuredto receive a left or right foot of a rider oriented generallyperpendicular to a direction of travel of the board; a wheel assemblyincluding exactly one wheel rotatable on an axle, wherein the wheel isdisposed between and extends above and below the first and second deckportions; a motor assembly configured to rotate the wheel about the axleto propel the vehicle; at least one sensor configured to measure anorientation of the board; a motor controller configured to receive boardorientation information measured by the at least one sensor and to causethe motor assembly to propel the vehicle based on the board orientationinformation; a suspension system including a pair of four-bar linkagescoupling opposing end portions of the axle to the first end portion ofthe frame, each of the four-bar linkages having a first fixed linkconnected to the axle, a second fixed link comprising the frame, and twopivotable links joining the first fixed link to the second fixed link,such that the board is configured to be movable up and down relative tothe axle; and a shock absorber having a first end coupled to the pair offour-bar linkages and a second end coupled to the first end portion ofthe frame, such that the shock absorber is configured to damp up anddown movement of the board relative to the axle.

In some embodiments, a self-balancing electric vehicle may include: aboard including a frame, a first deck portion disposed at a first endportion of the frame, and a second deck portion disposed at a second endportion of the frame, the first and second deck portions each configuredto receive a left or right foot of a rider oriented generallyperpendicular to a direction of travel of the board; a wheel assemblyincluding exactly one wheel rotatable on an axle, wherein the board istiltable about a fulcral axis defined by the axle and the wheel isdisposed between and extends above and below the first and second deckportions; a motor assembly configured to rotate the wheel about the axleto propel the vehicle; at least one sensor configured to measure atilting orientation of the board; a motor controller configured toreceive tilting orientation information measured by the at least onesensor and to cause the motor assembly to propel the vehicle based onthe tilting orientation information; a suspension system including afour-bar linkage coupling an end portion of the axle to the first endportion of the frame, the four-bar linkage having a first fixed linkconnected to the axle, a second fixed link comprising the frame, and twopivotable links joining the first fixed link to the second fixed link,such that the board is configured to move generally vertically relativeto the axle; and a shock absorber having a first end coupled to thefour-bar linkage and a second end coupled to the first end portion ofthe frame, such that the shock absorber is configured to damp generallyvertical movement of the board relative to the axle.

In some embodiments, a method of reducing the impact of uneven terrainon an electric vehicle may include: propelling a one-wheeled vehicleusing a motor assembly of the vehicle to rotate a wheel about an axleoriented generally perpendicular to a direction of travel of thevehicle, the vehicle comprising a board tiltable about a fulcral axisdefined by the axle, a first deck portion disposed at a first endportion of a frame of the board, and a second deck portion disposed at asecond end portion of the frame of the board, such that the wheel isdisposed between and extends above and below the first and second deckportions, wherein the first and second deck portions are each configuredto receive a left or right foot of a rider oriented generally parallelto the fulcral axis; causing the motor assembly to propel the vehiclebased on board tilt information determined by an onboard tilt sensor; inresponse to the wheel encountering an uneven support surface while beingpropelled, allowing generally vertical movement of the board relative tothe axle using a suspension system, wherein the suspension systemincludes a four-bar linkage coupling an end portion of the axle to thefirst end portion of the frame, the four-bar linkage having a firstfixed link connected to the axle, a second fixed link comprising theframe, and two pivotable links joining the first fixed link to thesecond fixed link; and damping the generally vertical movement of theboard relative to the axle using a shock absorber having a first endcoupled to the four-bar linkage and a second end coupled to the firstend portion of the frame.

Features, functions, and advantages may be achieved independently invarious embodiments of the present disclosure, or may be combined in yetother embodiments, further details of which can be seen with referenceto the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of an illustrative one-wheeled electricvehicle having a first suspension system in accordance with aspects ofthe present disclosure.

FIG. 2 is a top plan view of the vehicle of FIG. 1.

FIG. 3 is a bottom plan view of the vehicle of FIG. 1.

FIG. 4 is a side elevation view of the vehicle of FIG. 1.

FIG. 5 is an end elevation view of the vehicle of FIG. 1, taken from afirst end.

FIG. 6 is an end elevation view of the vehicle of FIG. 1, taken from asecond end.

FIG. 7 is a side elevation view of the vehicle of FIG. 1 with thesuspension system in a first configuration.

FIG. 8 is a side elevation view of the vehicle of FIG. 1 with thesuspension system in a second configuration.

FIG. 9 is an isometric view of another illustrative one-wheeled electricvehicle having a second suspension system in accordance with aspects ofthe present disclosure.

FIG. 10 is a top plan view of the vehicle of FIG. 9.

FIG. 11 is a bottom plan view of the vehicle of FIG. 9.

FIG. 12 is a side elevation view of the vehicle of FIG. 9.

FIG. 13 is an end elevation view of the vehicle of FIG. 9, taken from afirst end.

FIG. 14 is an end elevation view of the vehicle of FIG. 9, taken from asecond end.

FIG. 15 is a side elevation view of the vehicle of FIG. 9 with thesuspension system in a first configuration.

FIG. 16 is a side elevation view of the vehicle of FIG. 9 with thesuspension system in a second configuration.

FIG. 17 is a side elevation view of the vehicle of FIG. 9 with thesuspension system in a third configuration.

FIG. 18 is an isometric view of another illustrative one-wheeledelectric vehicle having a third suspension system in accordance withaspects of the present disclosure

FIG. 19 is a top plan view of the vehicle of FIG. 18.

FIG. 20 is a bottom plan view of the vehicle of FIG. 18.

FIG. 21 is a side elevation view of the vehicle of FIG. 18.

FIG. 22 is an end elevation view of the vehicle of FIG. 18, taken from afirst end.

FIG. 23 is an end elevation view of the vehicle of FIG. 18, taken from asecond end.

FIG. 24 is a side elevation view of the vehicle of FIG. 18 with thesuspension system in a first configuration.

FIG. 25 is a side elevation view of the vehicle of FIG. 18 with thesuspension system in a second configuration.

FIG. 26 is a side elevation view of the vehicle of FIG. 18 with thesuspension system in a third configuration.

FIG. 27 is a top plan view of the vehicle of FIG. 18 with the suspensionsystem in the first configuration.

FIG. 28 is a top plan view of the vehicle of FIG. 18 with the suspensionsystem in the second configuration.

FIG. 29 is a top plan view of the vehicle of FIG. 18 with the suspensionsystem in the third configuration.

FIG. 30 is a block diagram of illustrative electrical and electroniccomponents suitable for use with vehicles described herein.

DESCRIPTION

Various aspects and examples of suspension systems for one-wheeledvehicles, as well as related methods, are described below andillustrated in the associated drawings. Unless otherwise specified, asuspension system and/or its various components may, but are notrequired to, contain at least one of the structures, components,functionality, and/or variations described, illustrated, and/orincorporated herein. Furthermore, unless specifically excluded, theprocess steps, structures, components, functionalities, and/orvariations described, illustrated, and/or incorporated herein inconnection with the present teachings may be included in other similardevices and methods, including being interchangeable between disclosedembodiments. The following description of various examples is merelyillustrative in nature and is in no way intended to limit thedisclosure, its application, or uses. Additionally, the advantagesprovided by the examples and embodiments described below areillustrative in nature and not all examples and embodiments provide thesame advantages or the same degree of advantages.

Definitions

The following definitions apply herein, unless otherwise indicated.

“Substantially” means to be more-or-less conforming to the particulardimension, range, shape, concept, or other aspect modified by the term,such that a feature or component need not conform exactly. For example,a “substantially cylindrical” object means that the object resembles acylinder, but may have one or more deviations from a true cylinder.

“Comprising”,“including”, and “having” (and conjugations thereof) areused interchangeably to mean including but not necessarily limited to,and are open-ended terms not intended to exclude additional, unrecitedelements or method steps.

Terms such as “first”, “second”, and “third” are used to distinguish oridentify various members of a group, or the like, and are not intendedto show serial or numerical limitation.

The terms “up”,“down”,“inboard”,“outboard”,“over”,“under”, and the likeare intended to be understood in the context of a host vehicle on whichsystems described herein may be mounted or otherwise attached. Forexample, “outboard” may indicate a relative position that is laterallyfarther from the centerline of the vehicle, or a direction that is awayfrom the vehicle centerline. Conversely, “inboard” may indicate adirection toward the centerline, or a relative position that is closerto the centerline. Similarly, terms such as “over” and “under” or“above” and “below” should be interpreted with respect to the vehicle inits normal riding position on an underlying support surface. In theabsence of a host vehicle, the same directional terms may be used as ifthe vehicle were present. For example, even when viewed in isolation, acomponent may have a “top” edge, based on the fact that the componentwould be installed with the edge in question facing in upward.

“Coupled” means connected, either permanently or releasably, whetherdirectly or indirectly through intervening components.

Overview

In general, suspension systems according to the present teachings may besuitable for one-wheeled electric vehicles, such as a vehicle 10depicted in FIGS. 1-8, a vehicle 10′ depicted in FIGS. 9-17, and avehicle 10″ depicted in FIGS. 18-29. Apart from the various suspensionsystems, described further below, the construction of vehicles 10, 10′,and 10″ is substantially the same. Accordingly, for ease ofunderstanding, reference will be made below specifically (whereappropriate) only to vehicle 10. Corresponding components and featuresin vehicles 10′ and 10″ will have corresponding primed and double-primedreference numbers, respectively.

Vehicle 10 is a one-wheeled, self-stabilizing skateboard substantiallysimilar (in its non-suspension aspects) to the electric vehiclesdescribed in U.S. Pat. No. 9,101,817 (the '817 patent), the entirety ofwhich is hereby incorporated herein for all purposes. Accordingly,vehicle 10 includes a tiltable board 12 defining a riding plane andhaving a frame 14 supporting a first deck portion 16 and a second deckportion 18 (collectively referred to as the foot deck). Each deckportion 16, 18 is configured to receive a left or right foot of a rideroriented generally perpendicular to a direction of travel of the board,said direction of travel generally indicated at 20.

Vehicle 10 also includes a wheel assembly 22. Wheel assembly 22 includesa rotatable ground-contacting element 24 (e.g., a tire, wheel, orcontinuous track) disposed between and extending above the first andsecond deck portions 16, 18, and a hub motor 26 configured to rotateground-contacting element 24 to propel the vehicle. As shown in FIG. 1,vehicle 10 may include exactly one ground-contacting element. In someexamples, vehicle 10 may include two wheels disposed side by side(either adjacently or spaced apart) and sharing a common axis ofrotation.

As described in the '817 patent, vehicle 10 includes an electrical andelectronic component system 28, comprising at least one sensorconfigured to measure orientation information of the board, and a motorcontroller configured to receive orientation information measured by thesensor and to cause hub motor 26 to propel the skateboard based on theorientation information. Further details regarding electrical system 28are described with respect to FIG. 30.

Frame 14 may include any suitable structure configured to rigidlysupport the deck portions and to be coupled to an axle 32 of the wheelassembly, such that the weight of a rider may be supported on board 12having a fulcrum (also referred to as a fulcral axis) at the wheelassembly axle. Frame 14 may include one or more frame members, such asframe members 34 and 36, on which deck portions 16 and 18 may bemounted, and which may further support additional elements and featuresof the vehicle, such as a charging port, end bumpers, lightingassemblies, battery and electrical systems, electronics, controllers,and the like (not shown).

Deck portions 16 and 18 may include any suitable structures configuredto support the feet of a rider, such as non-skid surfaces, as well asvehicle-control features, such as a rider detection system. Illustrativedeck portions, including suitable rider detection systems, are describedin the '817 patent, as well as in U.S. Pat. No. 9,452,345, the entiretyof which is hereby included herein for all purposes.

Axle 32 (also referred to as a shaft) of hub motor 26 is coupled toframe 14 by a suspension system, damped by a damper or shock absorber.Various aspects and examples relating to suitable suspension systems aredescribed in greater detail below.

Examples, Components, and Alternatives

The following sections describe selected aspects of exemplary suspensionsystems for one-wheeled vehicles, as well as related systems and/ormethods. The examples in these sections are intended for illustrationand should not be interpreted as limiting the entire scope of thepresent disclosure. Each section may include one or more distinctembodiments or examples, and/or contextual or related information,function, and/or structure.

A. First Illustrative Suspension System: Four-bar Linkage

As shown in FIGS. 1-8, this section describes a first illustrativesuspension system 100 incorporated into vehicle 10. FIG. 1 is anisometric view of vehicle 10 and suspension system 100. FIG. 2 is a topplan view, FIG. 3 is a bottom plan view, and FIG. 4 is a side elevationview. FIGS. 5 and 6 are end elevation views of vehicle 10. FIGS. 7 and 8are side elevation views of the vehicle with the suspension system intwo different configurations (i.e., neutral and compressed).

As described above, vehicle 10 includes board 12 having frame 14. Firstdeck portion 16 is disposed at a first end portion 102 of the frame, andsecond deck portion 18 is disposed at a second end portion 104 of theframe. Wheel assembly 22 includes exactly one wheel (wheel 24) rotatableon axle 32, and the wheel is disposed between and extends above andbelow the first and second deck portions. Motor assembly 26 isconfigured to rotate the wheel about the axle to propel the vehicle,based on board orientation.

Suspension system 100 includes a pair of four-bar linkages couplingopposing end portions of the axle to the first end portion of the frame.Specifically, a first four-bar linkage 106 couples a first end portion108 of axle 32 to first end portion 102, and a second four-bar linkage110 couples a second end portion 112 of axle 32 to second end portion104. Four-bar linkage 106 is a planar four-bar linkage having a firstfixed link 114 connected to axle 32, a second fixed link 116 comprisingframe 14, and two pivotable links 118, 120 joining the first fixed linkto the second fixed link. Similarly, four-bar linkage 110 is a planarfour-bar linkage having a first fixed link 122 connected to axle 32, asecond fixed link 124 comprising frame 14, and two pivotable links 126,128 joining the first fixed link to the second fixed link. The movablelinks of four-bar linkages 106 and 110 move in generally parallelplanes, orthogonal to the riding plane defined by board 12. Accordingly,board 12 is configured to be movable up and down relative to axle 32.

This movement is damped by a shock absorber 130 having a first end 132coupled to the pair of four-bar linkages and a second end 134 coupled tothe first end portion of the frame. In this example, first end 132 ofshock absorber 130, also referred to as a compressible shock orcompressible shock absorber, is coupled at a rotating joint 138 to atransverse member 136 that joins pivotable links 120 and 128. Transversemember 136 may be fixed to or of a piece with links 120 and 128, suchthat transverse member 136 rotates when links 120 and 128 pivot. In someexamples, transverse member 136 and pivotable links 120, 128collectively form a U-shaped swing arm. Rotating joint 138 may be offsetfrom the transverse member, such that rotation of the transverse membercauses rotating joint 138 to move toward and away from first end 102 offrame 14.

As depicted in FIGS. 1-8, each of the pivotable links is coupled to thefirst fixed link by a first rotating joint and to the frame by a secondrotating joint. Specifically, upper pivotable link 118 is coupled tofirst fixed link 114 by a first rotating joint 140 and coupled to secondfixed link 116 by a second rotating joint 142. Lower pivotable link 120is coupled to first fixed link 114 by a first rotating joint 144 andcoupled to second fixed link 116 by a second rotating joint 146. On theother side of the vehicle, upper pivotable link 126 is coupled to firstfixed link 122 by a first rotating joint 148 and coupled to second fixedlink 124 by a second rotating joint 150. Lower pivotable link 128 iscoupled to first fixed link 122 by a first rotating joint 152 andcoupled to second fixed link 124 by a second rotating joint 154. In thisembodiment, for each of the four-bar linkages, the first rotating jointsare spaced farther apart than the second rotating joints. However, anysuitable spacing may be utilized, depending on the motion desired. Thisspacing may be facilitated by the shape and size of the first fixedlink. Specifically, first fixed links 114, 122 have a generallytriangular shape, with a smaller end fixed at the axle and a larger endextending toward first end portion 102 of frame 14.

Shock absorber 130 may be oriented generally parallel to the directionof travel of the vehicle, and second end 134 of the shock absorber maybe coupled to frame 14 at a pivotable joint 156 of a fixed transverseframe member 158. The shock absorber may be coupled to the frame usingany suitable structure or mechanism. Examples of shock absorber 130 mayinclude any suitable compressible shock configured to damp the expectedmovement of suspension system 100 and to bias the system in an operatingconfiguration. For example, shock absorber 130 may include a gas shockor a gas spring.

In some examples, the pivotable links may be referred to as rockers,such that each of the four-bar linkages comprises a double-rockerfour-bar linkage. In some examples, rotating joints may be referred toas revolute joints. As depicted in FIGS. 1-8, frame 14 may be coupled tothe wheel assembly by only suspension system 100. In some examples,second end portion 104 of the frame is unconnected or free-floating withrespect to the suspension system.

Based on the above description of vehicle 10 and suspension system 100,steps of a method for reducing the impact of uneven terrain on anelectric vehicle will now be described. A first step of the methodincludes propelling a one-wheeled vehicle using a motor assembly of thevehicle to rotate a wheel about an axle oriented generally perpendicularto a direction of travel of the vehicle. As described with respect tovehicle 10, the vehicle has a board tiltable about a fulcral axisdefined by the axle, a first deck portion disposed at a first endportion of a frame of the board, and a second deck portion disposed at asecond end portion of the frame of the board. The wheel is disposedbetween and extends above and below the first and second deck portions.The first and second deck portions are each configured to receive a leftor right foot of a rider oriented generally parallel to the fulcral axis(i.e., generally perpendicular to the direction of travel). A secondstep of the method includes causing the motor assembly to propel thevehicle based on board tilt information determined by an onboard tiltsensor. A third step of the method includes, in response to the wheelencountering an uneven support surface while being propelled, allowinggenerally vertical movement of the board relative to the axle using asuspension system. As described with respect to system 100, thesuspension system includes a four-bar linkage coupling an end portion ofthe axle to the first end portion of the frame. This four-bar linkagehas a first fixed link connected to the axle, a second fixed linkcomprising the frame, and two pivotable links joining the first fixedlink to the second fixed link. A fourth step of the method includesdamping the generally vertical movement of the board relative to theaxle using a shock absorber. As described, the shock absorber has afirst end coupled to the four-bar linkage and a second end coupled tothe first end portion of the frame.

With specific reference to FIGS. 7 and 8, relative motion of board 12with respect to axle 32 is depicted. In FIGS. 7 and 8, one of the sideframe members has been removed to better show the underlying components.FIG. 7 depicts vehicle 10 with suspension system 100 in a neutralconfiguration. Shock absorber 130 is extended, and pivotable links 118and 120 angle upward from the first fixed link to the frame. FIG. 8depicts vehicle 10 with suspension system 100 in a compressedconfiguration, where wheel 24 has been forced upward relative to board12, and the pivotable links have pivoted downward. By pivoting in thisfashion, transverse member 136 is rotated counterclockwise with respectto the drawings, thereby pivoting offset joint 138 and compressing shockabsorber 130.

B. Second Illustrative Suspension System: Watt's Linkage

As shown in FIGS. 9-17, this section describes a second illustrativesuspension system 200 incorporated into vehicle 10′. FIG. 9 is anisometric view of vehicle 10′ and suspension system 200. FIG. 10 is atop plan view, FIG. 11 is a bottom plan view, and FIG. 12 is a sideelevation view. FIGS. 13 and 14 are end elevation views. FIGS. 15-17 areside elevation views of the vehicle with the suspension system threedifferent configurations. As described above, vehicle 10′ includes board12′ having frame 14′. First deck portion 16′ is disposed at a first endportion 202 of the frame, and second deck portion 18′ is disposed at asecond end portion 204 of the frame. Wheel assembly 22′ includes exactlyone wheel (wheel 24′) rotatable on axle 32′, and the wheel is disposedbetween and extends above and below the first and second deck portions.Motor assembly 26′ is configured to rotate the wheel about the axle topropel the vehicle, based on board orientation. As shown in FIGS. 9-17,frame 14′ is coupled to wheel assembly 22′ by only suspension system200.

Suspension system 200 includes a pair of Watt's linkages 206, 208connecting opposing end portions of axle 32′ to frame 14′. Each of theWatt's linkages is substantially similar. Watt's linkage 206 includes acentral link 210 coupled to one end of axle 32′. Linkage 206 furtherincludes a first pivoting link 212 and a second pivoting link 214connecting the central link to the frame. Specifically, first pivotinglink 212 is coupled to a first end portion 216 of central link 210 at afirst rotating joint 218 and coupled to first end portion 202 of theframe at a second rotating joint 220. And second pivoting link 214 iscoupled to a second end portion 222 of the central link at a thirdrotating joint 224 and coupled to second end portion 204 of the frame ata fourth rotating joint 226. As depicted in the drawings, the secondrotating joint and the fourth rotating joint are disposed below the deckportions of the board.

Similarly, Watt's linkage 208 includes a central link 228 coupled to theother end of axle 32′. Linkage 208 further includes a first pivotinglink 230 and a second pivoting link 232 connecting the central link tothe frame. Specifically, first pivoting link 230 is coupled to a firstend portion 234 of central link 228 at a first rotating joint 236 andcoupled to first end portion 202 of the frame at a second rotating joint238. And second pivoting link 232 is coupled to a second end portion 240of the central link at a third rotating joint 242 and coupled to secondend portion 204 of the frame at a fourth rotating joint 244.Accordingly, the board is configured to be movable up and down on theWatt's linkages relative to the axle.

A shock absorber 246 has a first end 248 coupled to the pair of Watt'slinkages and a second end 250 coupled to the board, such that the shockabsorber is configured to damp movement of the board relative to theaxle. Specifically, first end 248 of shock absorber 246 is coupled to atransverse frame member 252 joining the pair of Watt's linkages, andsecond end 250 of shock absorber 246 is coupled to the board by a rockerarm 254. The rocker arm is coupled to transverse member 252 by a linkagemechanism 256, such that movement of the Watt's linkages pivots rockerarm 254 relative to the board. Because the shock is connected to therocker arm, pivoting of rocker arm 254 changes an effective length ofshock absorber 246.

With specific reference to FIGS. 15-17, relative motion of board 12′with respect to axle 32′ is depicted. In FIG. 15, board 12′ is at a lowposition with respect to axle 32′. In FIG. 16, board 12′ is at amid-position with respect to axle 32′. In FIG. 16, board 12′ is at ahigh position with respect to axle 32′. As shown in the drawings, thegenerally vertical movement of board 12′ with respect to axle 32′results in the outer ends of the linkage arms (i.e., pivotable links 212and 214) moving up and down while the central link rotates slightly.Pivoting of link 212 causes a pair of extension members 258, whichextend orthogonally from transverse member 252, to pivot as well.Extension members 258 are coupled to rocker arm 254 by a pivoting link260, such that pivoting of extension members 258 results in acorresponding pivoting of rocker arm 254 and alteration of the effectivelength of shock absorber 246. Linkage mechanism 256 comprises extensionmembers 258 and pivoting link 260.

C. Third Illustrative Suspension System: Transverse Damper

As shown in FIGS. 18-29, this section describes a third illustrativesuspension system 300 incorporated into vehicle 10″. FIG. 18 is anisometric view of vehicle 10″ and suspension system 300. FIG. 19 is atop plan view, FIG. 20 is a bottom plan view, and FIG. 21 is a sideelevation view. FIGS. 22 and 23 are end elevation views. FIGS. 24-29 areside and top views of the vehicle with the suspension system threedifferent configurations.

As described above, vehicle 10″ includes board 12″ having frame 14″.First deck portion 16″ is disposed at a first end portion 302 of theframe, and second deck portion 18″ is disposed at a second end portion304 of the frame. Wheel assembly 22″ includes exactly one wheel (wheel24″) rotatable on axle 32″, and the wheel is disposed between andextends above and below the first and second deck portions. Motorassembly 26″ is configured to rotate the wheel about the axle to propelthe vehicle, based on board orientation.

Suspension system 300 couples the wheel assembly to the board, such thatthe board is configured to be movable up and down relative to the axle.The suspension system includes a first pivotable link 306 and a secondpivotable link 308, each of which is coupled at a proximal end 310, 312to a respective end portion of axle 32″ and coupled at a distal end 314,316 to first end portion 302 of the frame by a distal rotating joint318, 320. System 300 further includes a first bell crank 322 and asecond bell crank 324 disposed above a plane defined by the first deckportion. Each of the bell cranks has a first moving pivot 326, 328 and asecond moving pivot 330, 332. The two bell cranks are rotatably coupledto first end portion 302 by a fixed pivot 334, 336, and oppose eachother across a width of board 12″.

A first pushrod 338 couples first pivotable link 306 to first movingpivot 326 of first bell crank 322, and a second pushrod 340 couplessecond pivotable link 308 to first moving pivot 328 of second bell crank324. In some examples, such as the one shown in FIGS. 18-29, thepushrods may be coupled to the pivotable links and the bell cranks atrotating joints that have orthogonal axes of rotation. In other words,pushrods 338 and 340 may each have two degrees of freedom.

A transversely-oriented shock absorber 342 is configured to dampmovement of the board relative to the axle. Accordingly, shock absorber342 has a first end 344 coupled to second moving pivot 330 of the firstbell crank and a second end 346 coupled to second moving pivot 332 ofthe second bell crank.

In some examples, vehicle 10″ further includes a transverse member 348joining the distal ends of the first and second pivotable links. In thisexample, frame 14″ is coupled to the wheel assembly by only suspensionsystem 300. Second end portion 304 of the frame is unconnected or freefloating with respect to the suspension system.

D. Illustrative Electrical Controls

FIG. 30 shows a block diagram of system 28, described briefly above,comprising various illustrative electrical components of vehicle 10,10′, or 10″, including onboard controls, some or all of which may beincluded in the vehicle. The electrical components may include a powersupply management system 400, a direct current to direct current (DC/DC)converter 404, a brushless direct current (BLDC) drive logic 406, apower stage 410, one or more 3-axis accelerometers 414, one or more hallsensors 418, and/or a motor temperature sensor 422. DC/DC converter 404,BLDC drive logic 406, and power stage 410 may be included in and/orconnected to a motor controller 424. Accelerometer(s) 414 may beincluded in the one or more orientation or tilt sensors 426 mentionedabove.

Active balancing (or self-stabilization) of the electric vehicle may beachieved through the use of a feedback control loop or mechanism. Thefeedback control mechanism may include sensors 426, which may beelectrically coupled to and/or included in motor controller 424.Preferably, the feedback control mechanism includes aProportional-Integral-Derivative (PID) control scheme using one or moregyros 428 and one or more accelerometers (e.g., accelerometer(s) 414).Gyro 428 may be configured to measure a pivoting of the board about itspitch axis (also referred to as the fulcral axis). Gyro 428 andaccelerometer 414 may be collectively configured to estimate (ormeasure, or sense) a lean angle of board 12, such as an orientation ofthe foot deck about the pitch, roll and/or yaw axes. In someembodiments, the gyro and accelerometer 414 may be collectivelyconfigured to sense orientation information sufficient to estimate thelean angle of frame 14, including pivotation about the pitch, rolland/or yaw axes.

As mentioned above, orientation information of board 12 may be measured(or sensed) by gyro 428 and accelerometer 414. The respectivemeasurements (or sense signals) from gyro 428 and accelerometer 414 maybe combined using a complementary or Kalman filter to estimate a leanangle of board 12 (e.g., pivoting of board 12 about the pitch, roll,and/or yaw axes, with pivoting about the pitch axis corresponding to apitch angle, pivoting about the roll axis corresponding to a roll orheel-toe angle, and pivoting about the yaw axis corresponding to aside-to-side yaw angle) while filtering out the impacts of bumps, roadtexture and disturbances due to steering inputs. For example, gyro 428and accelerometer 414 may be connected to microcontroller 430, which maybe configured to correspondingly measure movement of board 12 about andalong the pitch, roll, and/or yaw axes.

Alternatively, the electronic vehicle may include any suitable sensorand feedback control loop configured to self-stabilize a vehicle, suchas a 1-axis gyro configured to measure pivotation of the board about thepitch axis, a 1-axis accelerometer configured to measure a gravityvector, and/or any other suitable feedback control loop, such as aclosed-loop transfer function. Additional accelerometer and gyro axesmay allow improved performance and functionality, such as detecting ifthe board has rolled over on its side or if the rider is making a turn.

The feedback control loop may be configured to drive motor 26 to reducean angle of board 12 with respect to the ground. For example, if a riderwere to angle board 12 downward, so that first deck portion 16 waslower' than second deck portion 18 (e.g., if the rider pivoted board 12counterclockwise (CCW) in FIG. 1), then the feedback loop may drivemotor 26 to cause CCW rotation of tire 24 about the pitch axis (i.e.,axle 36) and a clockwise force on board 12.

Thus, motion of the electric vehicle may be achieved by the riderleaning his or her weight toward a selected (e.g., “front”) foot.Similarly, deceleration may be achieved by the rider leaning toward theother (e.g., “back” foot). Regenerative braking can be used to slow thevehicle. Sustained operation may be achieved in either direction by therider maintaining their lean toward either selected foot.

As indicated in FIG. 30, microcontroller 430 may be configured to send asignal to brushless DC (BLDC) drive logic 406, which may communicateinformation relating to the orientation and motion of board 12. BLDCdrive logic 406 may then interpret the signal and communicate with powerstage 410 to drive motor 26 accordingly. Hall sensors 418 may send asignal to the BLDC drive logic to provide feedback regarding asubstantially instantaneous rotational rate of the rotor of motor 26.Motor temperature sensor 422 may be configured to measure a temperatureof motor 26 and send this measured temperature to logic 406. Logic 406may limit an amount of power supplied to motor 26 based on the measuredtemperature of motor 26 to prevent the motor from overheating.

Certain modifications to the PID loop or other suitable feedback controlloop may be incorporated to improve performance and safety of theelectric vehicle. For example, integral windup may be prevented bylimiting a maximum integrator value, and an exponential function may beapplied to a pitch error angle (e.g., a measure or estimated pitch angleof board 12).

Alternatively or additionally, some embodiments may include neuralnetwork control, fuzzy control, genetic algorithm control, linearquadratic regulator control, state-dependent Riccati equation control,and/or other control algorithms. In some embodiments, absolute orrelative encoders may be incorporated to provide feedback on motorposition.

During turning, the pitch angle can be modulated by the heel-toe angle(e.g., pivoting of the board about the roll axis), which may improveperformance and prevent a front inside edge of board 12 from touchingthe ground. In some embodiments, the feedback loop may be configured toincrease, decrease, or otherwise modulate the rotational rate of thetire if the board is pivoted about the roll and/or yaw axes. Thismodulation of the rotational rate of the tire may exert an increasednormal force between a portion of the board and the rider, and mayprovide the rider with a sense of “carving” when turning, similar to thefeel of carving a snowboard through snow or a surfboard through water.

Once the rider has suitably positioned themselves on the board, thecontrol loop may be configured to not activate until the rider moves theboard to a predetermined orientation. For example, an algorithm may beincorporated into the feedback control loop, such that the control loopis not active (e.g., does not drive the motor) until the rider usestheir weight to bring the board up to an approximately level orientation(e.g., 0 degree pitch angle). Once this predetermined orientation isdetected, the feedback control loop may be enabled (or activated) tobalance the electric vehicle and to facilitate a transition of theelectric vehicle from a stationary mode (or configuration, or state, ororientation) to a moving mode (or configuration, or state, ororientation).

With continued reference to FIG. 30, the various electrical componentsmay be configured to manage a power supply 432. For example, powersupply management system 400 may be a battery management systemconfigured to protect batteries of power supply 432 from beingovercharged, over-discharged, and/or short-circuited. System 400 maymonitor battery health, may monitor a state of charge in power supply432, and/or may increase the safety of the vehicle. Power supplymanagement system 400 may be connected between a charge plug 434 ofvehicle 10 and power supply 432. The rider (or other user) may couple acharger to plug 434 and re-charge power supply 432 via system 400.

In operation, power switch 436 may be activated (e.g., by the rider).Activation of switch 436 may send a power-on signal to converter 404. Inresponse to the power-on signal, converter 404 may convert directcurrent from a first voltage level provided by power supply 432 to oneor more other voltage levels. The other voltage levels may be differentthan the first voltage level. Converter 404 may be connected to theother electrical components via one or more electrical connections toprovide these electrical components with suitable voltages.

Converter 404 (or other suitable circuitry) may transmit the power-onsignal to microcontroller 430. In response to the power-on signal,microcontroller may initialize sensors 426, and a rider detection device438.

The electric vehicle may include one or more safety mechanisms, such aspower switch 438 and/or rider detection device 438 to ensure that therider is on the board before engaging the feedback control loop. In someembodiments, rider detection device 438 may be configured to determineif the rider's feet are disposed on the foot deck, and to send a signalcausing motor 26 to enter an active state when the rider's feet aredetermined to be disposed on the foot deck.

Rider detection device 438 may include any suitable mechanism,structure, or apparatus for determining whether the rider is on theelectric vehicle. For example, device 438 may include one or moremechanical buttons, one or more capacitive sensors, one or moreinductive sensors, one or more optical switches, one or more forceresistive sensors, and/or one or more strain gauges. Rider detectiondevice 438 may be located on or under either or both of first and seconddeck portions 16, 18. In some examples, the one or more mechanicalbuttons or other devices may be pressed directly (e.g., if on the deckportions), or indirectly (e.g., if under the deck portions), to sensewhether the rider is on board 12. In some examples, the one or morecapacitive sensors and/or the one or more inductive sensors may belocated on or near a surface of either or both of the deck portions, andmay correspondingly detect whether the rider is on the board via achange in capacitance or a change in inductance. In some examples, theone or more optical switches may be located on or near the surface ofeither or both of the deck portions. The one or more optical switchesmay detect whether the rider is on the board based on an optical signal.In some examples, the one or more strain gauges may be configured tomeasure board or axle flex imparted by the rider's feet to detectwhether the rider is on the board. In some embodiments, device 438 mayinclude a hand-held “dead-man” switch.

If device 438 detects that the rider is suitably positioned on theelectric vehicle, then device 438 may send a rider-present signal tomicrocontroller 430. The rider-present signal may be the signal causingmotor 26 to enter the active state. In response to the rider-presentsignal (and/or, for example, the board being moved to the levelorientation), microcontroller 430 may activate the feedback control loopfor driving motor 26. For example, in response to the rider-presentsignal, microcontroller 430 may send board orientation information (ormeasurement data) from sensors 426 to logic 406 for powering motor 26via power stage 410.

In some embodiments, if device 438 detects that the rider is no longersuitably positioned or present on the electric vehicle, device 438 maysend a rider-not-present signal to microcontroller 430. In response tothe rider-not-present signal, circuitry of vehicle 10 (e.g.,microcontroller 430, logic 406, and/or power stage 410) may beconfigured to reduce a rotational rate of the rotor relative to thestator to bring vehicle 10 to a stop. For example, the electric coils ofthe rotor may be selectively powered to reduce the rotational rate ofthe rotor. In some embodiments, in response to the rider-not-presentsignal, the circuitry may be configured to energize the electric coilswith a relatively strong and/or substantially continuously constantvoltage, to lock the rotor relative to the stator, to prevent the rotorfrom rotating relative to the stator, and/or to bring the rotor to asudden stop.

In some embodiments, the vehicle may be configured to actively drivemotor 26 even though the rider may not be present on the vehicle (e.g.,temporarily), which may allow the rider to perform various tricks. Forexample, device 438 may be configured to delay sending therider-not-present signal to the microcontroller for a predeterminedduration of time, and/or the microcontroller may be configured to delaysending the signal to logic 406 to cut power to the motor for apredetermined duration of time.

E. Additional Examples and Illustrative Combinations

This section describes additional aspects and features of illustrativesuspension systems for one-wheeled electric vehicles, presented withoutlimitation as a series of paragraphs, some or all of which may bealphanumerically designated for clarity and efficiency. Each of theseparagraphs can be combined with one or more other paragraphs, and/orwith disclosure from elsewhere in this application, in any suitablemanner. Some of the paragraphs below expressly refer to and furtherlimit other paragraphs, providing without limitation examples of some ofthe suitable combinations.

A0. A self-balancing electric vehicle, comprising:

-   -   a board including a frame, a first deck portion disposed at a        first end portion of the frame, and a second deck portion        disposed at a second end portion of the frame, the first and        second deck portions each configured to receive a left or right        foot of a rider oriented generally perpendicular to a direction        of travel of the board;

a wheel assembly including exactly one wheel rotatable on an axle,wherein the wheel is disposed between and extends above and below thefirst and second deck portions;

-   -   a motor assembly configured to rotate the wheel about the axle        to propel the vehicle;    -   at least one sensor configured to measure an orientation of the        board;    -   a motor controller configured to receive board orientation        information measured by the at least one sensor and to cause the        motor assembly to propel the vehicle based on the board        orientation information;    -   a suspension system including a pair of four-bar linkages        coupling opposing end portions of the axle to the first end        portion of the frame, each of the four-bar linkages having a        first fixed link connected to the axle, a second fixed link        comprising the frame, and two pivotable links joining the first        fixed link to the second fixed link, such that the board is        configured to be movable up and down relative to the axle; and    -   a shock absorber having a first end coupled to the pair of        four-bar linkages and a second end coupled to the first end        portion of the frame, such that the shock absorber is configured        to damp up and down movement of the board relative to the axle.

A1. The vehicle of A0, wherein each of the four-bar linkages comprises adouble-rocker four-bar linkage.

A2. The vehicle of any one of paragraphs A0 through A1, wherein each ofthe pivotable links is coupled to the first fixed link by a firstrotating joint and coupled to the frame by a second rotating joint.

A3. The vehicle of A2, wherein, for each of the four-bar linkages, thesecond rotating joints of the pivotable links are closer together thanthe first rotatable joints.

A4. The vehicle of any one of paragraphs A0 through A3, furthercomprising a transverse member extending across the frame generallyperpendicular to the direction of travel, the transverse memberconnecting an opposing pair of the pivotable links of the four-barlinkages.

A5. The vehicle of A4, wherein the transverse member is configured torotate as the board moves up and down relative to the axle.

A6. The vehicle of A4, wherein the first end of the shock absorber iscoupled to the transverse member.

A7. The vehicle of any one of paragraphs A0 through A6, wherein theframe is coupled to the wheel assembly by only the suspension system.

A8. The vehicle of A7, wherein the second end portion of the frame isunconnected with respect to the suspension system.

B0. A self-balancing electric vehicle, comprising:

-   -   a board including a frame, a first deck portion disposed at a        first end portion of the frame, and a second deck portion        disposed at a second end portion of the frame, the first and        second deck portions each configured to receive a left or right        foot of a rider oriented generally perpendicular to a direction        of travel of the board;    -   a wheel assembly including exactly one wheel rotatable on an        axle, wherein the board is tiltable about a fulcral axis defined        by the axle and the wheel is disposed between and extends above        and below the first and second deck portions;    -   a motor assembly configured to rotate the wheel about the axle        to propel the vehicle;    -   at least one sensor configured to measure a tilting orientation        of the board;    -   a motor controller configured to receive tilting orientation        information measured by the at least one sensor and to cause the        motor assembly to propel the vehicle based on the tilting        orientation information;    -   a suspension system including a four-bar linkage coupling an end        portion of the axle to the first end portion of the frame, the        four-bar linkage having a first fixed link connected to the        axle, a second fixed link comprising the frame, and two        pivotable links joining the first fixed link to the second fixed        link, such that the board is configured to move generally        vertically relative to the axle; and    -   a shock absorber having a first end coupled to the four-bar        linkage and a second end coupled to the first end portion of the        frame, such that the shock absorber is configured to damp        generally vertical movement of the board relative to the axle.

B1. The vehicle of B0, wherein each of the pivotable links is coupled tothe first fixed link by a first rotating joint and coupled to the frameby a second rotating joint.

B2. The vehicle of B1, wherein the second rotating joints of thepivotable links are closer together than the first rotatable joints.

B3. The vehicle of any one of paragraphs B0 through B2, wherein theframe is coupled to the wheel assembly by only the suspension system.

B4. The vehicle of B3, wherein the second end portion of the frame isunconnected with respect to the suspension system.

C0. A method of reducing the impact of uneven terrain on an electricvehicle, the method comprising:

-   -   propelling a one-wheeled vehicle using a motor assembly of the        vehicle to rotate a wheel about an axle oriented generally        perpendicular to a direction of travel of the vehicle, the        vehicle comprising a board tiltable about a fulcral axis defined        by the axle, a first deck portion disposed at a first end        portion of a frame of the board, and a second deck portion        disposed at a second end portion of the frame of the board, such        that the wheel is disposed between and extends above and below        the first and second deck portions, wherein the first and second        deck portions are each configured to receive a left or right        foot of a rider oriented generally parallel to the fulcral axis;    -   causing the motor assembly to propel the vehicle based on board        tilt information determined by an onboard tilt sensor;    -   in response to the wheel encountering an uneven support surface        while being propelled, allowing generally vertical movement of        the board relative to the axle using a suspension system,        wherein the suspension system includes a four-bar linkage        coupling an end portion of the axle to the first end portion of        the frame, the four-bar linkage having a first fixed link        connected to the axle, a second fixed link comprising the frame,        and two pivotable links joining the first fixed link to the        second fixed link; and    -   damping the generally vertical movement of the board relative to        the axle using a shock absorber having a first end coupled to        the four-bar linkage and a second end coupled to the first end        portion of the frame.

C1. The method of C0, wherein each of the pivotable links is coupled tothe first fixed link by a first rotating joint and coupled to the frameby a second rotating joint.

C2. The method of C1, wherein the second rotating joints of thepivotable links are closer together than the first rotatable joints.

C3. The method of any one of paragraphs C0 through C2, wherein the frameis coupled to the wheel by only the suspension system.

C4. The method of C3, wherein the second end portion of the frame isunconnected with respect to the suspension system.

C5. The method of any one of paragraphs C0 through C4, wherein the motorassembly comprises a hub motor.

D0. A self-balancing electric vehicle, comprising:

-   -   a board including a frame, a first deck portion disposed at a        first end portion of the frame, and a second deck portion        disposed at a second end portion of the frame, the first and        second deck portions each configured to receive a left or right        foot of a rider oriented generally perpendicular to a direction        of travel of the board;    -   a wheel assembly including exactly one wheel rotatable on an        axle, wherein the wheel is disposed between and extends above        and below the first and second deck portions;    -   a motor assembly configured to rotate the wheel about the axle        to propel the vehicle;    -   at least one sensor configured to measure orientation        information of the board;    -   a motor controller configured to receive orientation information        measured by the at least one sensor and to cause the motor        assembly to propel the vehicle based on the orientation        information;    -   a suspension system comprising a pair of Watt's linkages        connecting opposing end portions of the axle to the frame, each        of the Watt's linkages including a central link coupled to the        axle of the wheel, a first pivoting link coupled to a first end        portion of the central link at a first rotating joint and        coupled to the first end portion of the frame at a second        rotating joint, and a second pivoting link coupled to a second        end portion of the central link at a third rotating joint and        coupled to the second end portion of the frame at a fourth        rotating joint, such that the board is configured to be movable        up and down relative to the axle; and    -   a shock absorber having a first end coupled to the pair of        Watt's linkages and a second end coupled to the board, such that        the shock absorber is configured to damp movement of the board        relative to the axle.

D1. The vehicle of D0, wherein the first end of the shock absorber iscoupled to a transverse member joining the pair of Watt's linkages andthe second end of the shock absorber is coupled to the board by a rockerarm.

D2. The vehicle of D1, wherein the rocker arm is coupled to thetransverse member by a linkage mechanism, such that movement of theWatt's linkages pivots the rocker arm relative to the board and changesan effective length of the shock absorber.

D3. The vehicle of any one of paragraphs D0 through D2, wherein theframe is coupled to the wheel assembly by only the suspension system.

D4. The vehicle of any one of paragraphs D0 through D3, wherein thesecond rotating joint and the fourth rotating joint are disposed belowthe deck portions of the board.

E0 A self-balancing electric vehicle, comprising:

-   -   a board including a frame, a first deck portion disposed at a        first end portion of the frame, and a second deck portion        disposed at a second end portion of the frame, the first and        second deck portions each configured to receive a left or right        foot of a rider oriented generally perpendicular to a direction        of travel of the board;    -   a wheel assembly including exactly one wheel rotatable on an        axle, wherein the wheel is disposed between and extends above        and below the first and second deck portions;    -   a motor assembly configured to rotate the wheel about the axle        to propel the vehicle;    -   at least one sensor configured to measure orientation        information of the board;    -   a motor controller configured to receive orientation information        measured by the at least one sensor and to cause the motor        assembly to propel the vehicle based on the orientation        information; and    -   a suspension system coupling the wheel assembly to the board,        such that the board is configured to be movable up and down        relative to the axle, the suspension system including:    -   a first and a second pivotable link, each of the pivotable links        coupled at a proximal end to a respective end portion of the        axle and coupled at a distal end to the first end portion of the        frame by a distal rotating joint;    -   a first bell crank and a second bell crank, the first and second        bell cranks opposing each other across a width of the board,        wherein each of the bell cranks respectively has a first and a        second moving pivot and is rotatably coupled to the first end        portion of the frame by a respective fixed pivot;    -   a first pushrod coupling the first pivotable link to the first        moving pivot of the first bell crank, and a second pushrod        coupling the second pivotable link to the first moving pivot of        the second bell crank; and    -   a shock absorber having a first end coupled to the second moving        pivot of the first bell crank and a second end coupled to the        second moving pivot of the second bell crank, such that the        shock absorber is configured to damp movement of the board        relative to the axle.

E1. The vehicle of E0, wherein the first pushrod is coupled to the firstpivotable link at a first rotating joint and coupled to the first bellcrank at a second rotating joint, the first and second rotating jointshaving orthogonal axes of rotation.

E2. The vehicle of any one of paragraphs E0 through E1, furthercomprising a transverse member joining the distal ends of the first andsecond pivotable links.

E3. The vehicle of any one of paragraphs E0 through E2, wherein the bellcranks are disposed above a plane defined by the first deck portion.

E4. The vehicle of any one of paragraphs E0 through E3, wherein theframe is coupled to the wheel assembly by only the suspension system.

E5. The vehicle of E4, wherein the second end portion of the frame isunconnected to the suspension system.

Conclusion

The disclosure set forth above may encompass multiple distinct exampleswith independent utility. Although each of these has been disclosed inits preferred form(s), the specific embodiments thereof as disclosed andillustrated herein are not to be considered in a limiting sense, becausenumerous variations are possible. To the extent that section headingsare used within this disclosure, such headings are for organizationalpurposes only. The subject matter of the disclosure includes all noveland nonobvious combinations and subcombinations of the various elements,features, functions, and/or properties disclosed herein. The followingclaims particularly point out certain combinations and subcombinationsregarded as novel and nonobvious. Other combinations and subcombinationsof features, functions, elements, and/or properties may be claimed inapplications claiming priority from this or a related application. Suchclaims, whether broader, narrower, equal, or different in scope to theoriginal claims, also are regarded as included within the subject matterof the present disclosure.

What is claimed is:
 1. A self-balancing electric vehicle, comprising: aboard including a frame, a first deck portion disposed at a first endportion of the frame, and a second deck portion disposed at a second endportion of the frame, the first and second deck portions each configuredto receive a left or right foot of a rider oriented generallyperpendicular to a direction of travel of the board; a wheel assemblyincluding exactly one wheel rotatable on an axle, wherein the wheel isdisposed between and extends above and below the first and second deckportions; a motor assembly configured to rotate the wheel about the axleto propel the vehicle; at least one sensor configured to measure anorientation of the board; a motor controller configured to receive boardorientation information measured by the at least one sensor and to causethe motor assembly to propel the vehicle based on the board orientationinformation; a suspension system including a pair of four-bar linkagescoupling opposing end portions of the axle to the first end portion ofthe frame, each of the four-bar linkages having a first fixed linkconnected to the axle, a second fixed link comprising the frame, and twopivotable links joining the first fixed link to the second fixed link,such that the board is configured to be movable up and down relative tothe axle; and a shock absorber having a first end coupled to the pair offour-bar linkages and a second end coupled to the first end portion ofthe frame, such that the shock absorber is configured to damp up anddown movement of the board relative to the axle.
 2. The vehicle of claim1, wherein each of the four-bar linkages comprises a double-rockerfour-bar linkage.
 3. The vehicle of claim 1, wherein each of thepivotable links is coupled to the first fixed link by a first rotatingjoint and coupled to the frame by a second rotating joint.
 4. Thevehicle of claim 3, wherein, for each of the four-bar linkages, thesecond rotating joints of the pivotable links are closer together thanthe first rotatable joints.
 5. The vehicle of claim 1, furthercomprising a transverse member extending across the frame generallyperpendicular to the direction of travel, the transverse memberconnecting an opposing pair of the pivotable links of the four-barlinkages.
 6. The vehicle of claim 5, wherein the transverse member isconfigured to rotate as the board moves up and down relative to theaxle.
 7. The vehicle of claim 5, wherein the first end of the shockabsorber is coupled to the transverse member.
 8. The vehicle of claim 1,wherein the frame is coupled to the wheel assembly by only thesuspension system.
 9. The vehicle of claim 8, wherein the second endportion of the frame is unconnected with respect to the suspensionsystem.
 10. A self-balancing electric vehicle, comprising: a boardincluding a frame, a first deck portion disposed at a first end portionof the frame, and a second deck portion disposed at a second end portionof the frame, the first and second deck portions each configured toreceive a left or right foot of a rider oriented generally perpendicularto a direction of travel of the board; a wheel assembly includingexactly one wheel rotatable on an axle, wherein the board is tiltableabout a fulcral axis defined by the axle and the wheel is disposedbetween and extends above and below the first and second deck portions;a motor assembly configured to rotate the wheel about the axle to propelthe vehicle; at least one sensor configured to measure a tiltingorientation of the board; a motor controller configured to receivetilting orientation information measured by the at least one sensor andto cause the motor assembly to propel the vehicle based on the tiltingorientation information; a suspension system including a four-barlinkage coupling an end portion of the axle to the first end portion ofthe frame, the four-bar linkage having a first fixed link connected tothe axle, a second fixed link comprising the frame, and two pivotablelinks joining the first fixed link to the second fixed link, such thatthe board is configured to move generally vertically relative to theaxle; and a shock absorber having a first end coupled to the four-barlinkage and a second end coupled to the first end portion of the frame,such that the shock absorber is configured to damp generally verticalmovement of the board relative to the axle.
 11. The vehicle of claim 10,wherein each of the pivotable links is coupled to the first fixed linkby a first rotating joint and coupled to the frame by a second rotatingjoint.
 12. The vehicle of claim 11, wherein the second rotating jointsof the pivotable links are closer together than the first rotatablejoints.
 13. The vehicle of claim 10, wherein the frame is coupled to thewheel assembly by only the suspension system.
 14. The vehicle of claim13, wherein the second end portion of the frame is unconnected withrespect to the suspension system.
 15. A method of reducing the impact ofuneven terrain on an electric vehicle, the method comprising: propellinga one-wheeled vehicle using a motor assembly of the vehicle to rotate awheel about an axle oriented generally perpendicular to a direction oftravel of the vehicle, the vehicle comprising a board tiltable about afulcral axis defined by the axle, a first deck portion disposed at afirst end portion of a frame of the board, and a second deck portiondisposed at a second end portion of the frame of the board, such thatthe wheel is disposed between and extends above and below the first andsecond deck portions, wherein the first and second deck portions areeach configured to receive a left or right foot of a rider orientedgenerally parallel to the fulcral axis; causing the motor assembly topropel the vehicle based on board tilt information determined by anonboard tilt sensor; in response to the wheel encountering an unevensupport surface while being propelled, allowing generally verticalmovement of the board relative to the axle using a suspension system,wherein the suspension system includes a four-bar linkage coupling anend portion of the axle to the first end portion of the frame, thefour-bar linkage having a first fixed link connected to the axle, asecond fixed link comprising the frame, and two pivotable links joiningthe first fixed link to the second fixed link; and damping the generallyvertical movement of the board relative to the axle using a shockabsorber having a first end coupled to the four-bar linkage and a secondend coupled to the first end portion of the frame.
 16. The method ofclaim 15, wherein each of the pivotable links is coupled to the firstfixed link by a first rotating joint and coupled to the frame by asecond rotating joint.
 17. The method of claim 16, wherein the secondrotating joints of the pivotable links are closer together than thefirst rotatable joints.
 18. The method of claim 15, wherein the frame iscoupled to the wheel by only the suspension system.
 19. The method ofclaim 18, wherein the second end portion of the frame is unconnectedwith respect to the suspension system.
 20. The method of claim 15,wherein the motor assembly comprises a hub motor.